A geared motor unit for valve control described in European patent application EP1217192 is particularly well known in the state of the art. This prior art document describes a motor controlling connection grids through a gear system. A magnetic sensor is provided opposite the end of the output shaft, which includes a magnet at the end of the shaft associated with flow concentrators.
This solution is not satisfactory for several reasons. First of all, the electromechanical architecture has a large footprint, which does not allow for a compact design. Secondly, the connection of the various electrical components requires the use of connection technology, which is a source of failure. Thirdly, this solution is incompatible with an application requiring a hollow shaft. Finally, this embodiment involves extending the output shaft to enable the magnet to be positioned after the shaft has been guided.
The invention aims to remedy these drawbacks by offering a very compact and robust solution that significantly reduces connectivity. One of the aims of the invention is to reduce to a minimum the problems of reliability resulting from the electrical connection of the various components of a geared motor unit, and in particular the connection of the coils with the control circuit, the connection of the position sensor with this control circuit and the connection with the connector of the geared motor unit. The aim is to reduce the risk of failures and also to simplify assembly, for industrial mass-production.
Another aim is to improve compactness, by optimizing the positioning of the main components of the geared motor unit, namely the electromagnetic actuator, the gear train and the electronic circuit and by minimizing unused spaces. Another aim is to ensure optimal mechanical strength and guidance of the gear train and especially of the output shaft, through perfect precision and mechanical robustness of the drive, even when the geared motor unit is subjected to high forces. An optional aim is to enable one embodiment with a through output shaft.
In order to be able to produce a compact and integrated assembly that can be used in an industrial context, another one of the objects of the invention is to be able to form an assembly integrating a function such as a valve body by forming an integral stem with the housing of the geared motor unit. For this purpose, the invention in its most general sense relates to a geared motor unit consisting of a housing comprising an electric motor formed of a coiled stator assembly and a magnetized rotor, said housing further comprising a printed circuit board for connecting and controlling the motor, a train of motion-reducing gears, a sensor magnet and a magneto-sensitive probe, the train of gears comprising a toothed movement output gear, the sensor magnet being ring-shaped and being rigidly connected with said output gear, characterized in that                said output gear is extended on either side of the sensor magnet by two guides cooperating with the two opposite walls of the housing,        said ring-shaped magnet surrounds the axis of rotation of the output gear,        said printed circuit board includes the means for controlling said motor and extends to the vicinity of the output gear,        said printed circuit board comprises, in the area located in the vicinity of the output gear, said magneto-sensitive probe connected directly electrically and mechanically to said area and located opposite, axially or radially, said ring-shaped magnet.        
Preferably, the magnetization direction of said sensor magnet has at least one angularly variable component. Preferably also, the rotor is extended by a pinion and said pinion and the toothed output gear bearing said ring-shaped magnet are located on either side of said printed circuit board. In a particular embodiment, the magneto-sensitive probe is connected to the printed circuit board on the surface opposite the one bearing most of the other electronic components.
In an alternative embodiment, the gear train includes intermediate toothed gears located on one side of the printed circuit board and the toothed output gear is located on the opposite side of the printed circuit board. Alternatively, the rotor is extended by a pinion on one side of said printed circuit, said gear train having a series of intermediate toothed gears driving the toothed output gear located on the opposite side of said printed circuit board. The geared motor unit can have a common shaft with two intermediate toothed gears and said printed circuit board can be traversed by the shaft of the output toothed gear or by the shaft of the rotor of the actuator.
Advantageously, said permanent magnet has an angularly variable magnetization direction and a tubular shape, the magneto-sensitive probe being placed in a radial position with respect to said magnet. The invention makes it possible to produce a hollow toothed output gear shaft going through said housing. Advantageously, said housing includes means for guiding each of the ends of the shaft of the toothed output gear on either side of the printed circuit board. Preferably, the toothed output gear is coaxial with the rotor.
In order to form an integrated assembly, said housing can integrate a stem blocked by a movable flap rigidly connected to and controlled by the toothed output gear. The housing casings then directly integrate this stem (obtained by moulding a plastic or metal material for example). The invention can advantageously be applied to an air conditioning valve having a rotating flap activated by the shaft of the geared motor unit toothed output gear, or to an air shutter comprising at least one movable flap activated by the shaft of the geared motor unit toothed output gear, or to a throttle body for automotive air intake comprising at least one movable flap actuated by the shaft of the geared motor unit toothed output gear, or a turbocharger relief valve comprising at least one movable lever actuated by the shaft of the geared motor unit toothed output gear. The control of water valves, of the thermostat type, is particularly addressed by this invention.